[tylerhart_21]

Looking on the internet, you find a lot of different companies making airboxes for the 325i/328i/330i. Kal-905 on one series forums (Making an Eventuri for the n52) sparked this idea. I was thinking of taking the Gruppe-M style airboxes, enclosing them, and adding an opening on the bottom for a Dinan ram intake.

Why:
-Enclosing the airbox would help with not allowing hot air into the intake
-Sound (Smooth airbox)
-HP/Flow (Maybe 5HP and more direct flow)
-Something different

Problems:
-Enclosing the airbox (No opening for cleaning/changing the air filter)
-Time (It's going to take some trial and error)
-No changes over the standard airbox
-Could cost some money

Right now, I have an idea. I don't have the program to test or design the airbox. Since I am in college, this will be on the back burner, and I have limited resources. (I will try to update when available)

With everything laid out, I will have to do some more research. If this is a good idea to pursue, then the best first step to test the idea by getting the air intake and testing it open versus closed. The easy way when testing the air box closed would be to use tape to close it. (Testing will look at the air temps "Bimmerlink")

With this being said, I want to know what you guys think and if you have any suggestions.

Disclaimer: This idea wouldn't push huge horsepower numbers, more than likely, you will hear more induction noise.

[AmuroRay]

It’s not about “cold air” it’s about intake length for optimal resonance, and a good size filter with a velocity stack to keep air velocity up.

[Biginboca]

I think you are making this too difficult. Just pick up a euro Airbox for under $200 off eBay Germany (it is a proper oem sealed Airbox which has easy filter changes and a filter as large as any of the **rip off** aftermarket intakes) and then do this:

https://www.e90post.com/forums/showthread.php?t=1696371

You will be ~$220 and a couple hours time into what I believe is the best sounding and performing Airbox set up you can have except for ITB’s

[yupetc]

I concur with Big Boca above, just get an Euro Box and call it. It's pretty much the best bang for the buck and it stays OEM looking so you don't raise anyone's eyebrows if you'd like to lay low.

I have a set of AA headers and that Euro Box that I plan on selling in a few months. They've been taken out of the car two weeks ago, will clean them up and bundle them together for sale. Let me know if you're interested.

[AmuroRay]

I’m actually not in agreement with these guys - I dyno tested all three of the majors setups, the Stock airbox with a drop in, the Injen intake, and a AFE.

The AFE had the most peak power, but the Injen actually had the most broad powerband of all of them - by a lot. It was making almost 10whp/tq more I think in the mid range - it was claimed because Injen had a resonance tuned intake tube compared to the others.
Peak power was 1-2whp off the AFE.

The stock Airbox wasn’t bad, it was right in the mix, but didn’t offer the same gains under the curve that the other two did.

[The Nightman]

Originally Posted by Biginboca

I think you are making this too difficult. Just pick up a euro Airbox for under $200 off eBay Germany (it is a proper oem sealed Airbox which has easy filter changes and a filter as large as any of the **rip off** aftermarket intakes) and then do this:

https://www.e90post.com/forums/showthread.php?t=1696371

You will be ~$220 and a couple hours time into what I believe is the best sounding and performing Airbox set up you can have except for ITB’s

This is the way

[The Nightman]

Originally Posted by AmuroRay

I’m actually not in agreement with these guys - I dyno tested all three of the majors setups, the Stock airbox with a drop in, the Injen intake, and a AFE.

The AFE had the most peak power, but the Injen actually had the most broad powerband of all of them - by a lot. It was making almost 10whp/tq more I think in the mid range - it was claimed because Injen had a resonance tuned intake tube compared to the others.
Peak power was 1-2whp off the AFE.

The stock Airbox wasn’t bad, it was right in the mix, but didn’t offer the same gains under the curve that the other two did.

Very interesting. Do you have a link to more details?

[chilledn52]

Honestly, I got myself a 3d printer so i am mocking up a MAF adapter for the vehicle. Got one modeled for a 4 inch inlet to the 3 inch with the maf port.
Gonna try to model the snorkel for the hose to enter the airbox.

[AmuroRay]

.my old stock intake with a snorkel vs a long tube intake on my DISA M52tuB25 Z3.

The tube style intake walked all over the snorkel style intake in the stock box. Modified box pictured.

[AmuroRay]

3 intakes tested on my N52 E90 - Red is Injen, Blue is AFE, green is the stock airbox with a drop in and I think a hose - could be wrong.

[Biginboca]

AmuroRay That is great info thanks for posting it. One variable is the stock Airbox uses a panel filter and the injen and AFE used a large cone filter. So that is a big variable the surface area of the cone filters is like 50% larger when I measured it. That is one variable that your dyno wouldn’t account for, it’s not comparing to a Euro Airbox which has a large cone filter also.

Just to reiterate, the euro Airbox also has a large cone filter like the afe and the injen. The US Airbox has a much smaller surface area flat panel filter.

I still believe the Euro Airbox with a ram intake is going to be as good or likely better than any aftermarket N52 Airbox.

Just a stock (non euro) US Airbox with ram and silicone TB hose was dyno’ed at like 17hp peak hp over stock, which is superior to afe (claimed by AFE to produce 12hp*).

This dyno below is for stock vs a U.S. Airbox (not Euro) with k&n drop in filter, ram hose mod I linked above, and a silicone Airbox to TB hose. It shows average gains of like 13hp and 16ft/lbs, and peak of 17hp and 17 ft/lbs. I know there would be even more gains than this if the Airbox on this dyno was a euro one:



* AFE claim is this: This Stage 2 Sealed Intake produces 12HP, 15LBS. x FT. of torque and outflows the factory intake by 56%.

[Biginboca]

Also I want to remind everyone that I had lean codes the whole time I ran the AFE Airbox as did multiple other users of this Airbox when I searched. It not only isn’t as good as a Euro Airbox it potentially damages your engine because the MAF section is oversized compared to stock MAF section and therefor our DME can’t calculate the airflow properly. I made a thread about this and listed the users of this Airbox whom all reported lean codes using the AFE.

AmuroRay, you were one of them… and you said you thought it led to your fuel pump failing! So that alone disqualifies it as even being considered because aftermarket parts that damage our cars are not even worth running in my opinion.

[AmuroRay]

Originally Posted by Biginboca

Also I want to remind everyone that I had lean codes the whole time I ran the AFE Airbox as did multiple other users of this Airbox when I searched. It not only isn’t as good as a Euro Airbox it potentially damages your engine because the MAF section is oversized compared to stock MAF section and therefor our DME can’t calculate the airflow properly. I made a thread about this and listed the users of this Airbox whom all reported lean codes using the AFE.

AmuroRay, you were one of them… and you said you thought it led to your fuel pump failing! So that alone disqualifies it as even being considered because aftermarket parts that damage our cars are not even worth running in my opinion.

I don’t recall that last part, I thought my pump failed from running it down with E85 in the tank, but I could be wrong.

Scott’s dyno was not from the intake, no matter what he thinks - that’s clearly something else going on, possible adaptations or a new map, but that isn’t an intake doing that.

I had the Euro Intake as well; it’s filter surface area is smaller than the Injen and AFE. It still uses the sock opening and doesn’t offer another route for air. It’s ok, and none of these things will add big power, but I do think there is an improvement to be had - namely a larger tube style intake.

[chilledn52]

Originally Posted by Biginboca

It not only isn’t as good as a Euro Airbox it potentially damages your engine because the MAF section is oversized compared to stock MAF section and therefor our DME can’t calculate the airflow properly.

Question on this MAF diameter then. Since im tinkering around with a maf adapter for a cone filter to attach. If i have a 4 inch inlet for the cone and downsize to a approx 3 inch pipe before the maf, would you assume problems will occur?
Cause if the diameter of the pipe at the point of the maf is the same as stock, then it should calculate the proper lamda. Just allowing more of a ram air effect within the pipe.

[Biginboca]

Originally Posted by chilledn52

Question on this MAF diameter then. Since im tinkering around with a maf adapter for a cone filter to attach. If i have a 4 inch inlet for the cone and downsize to a approx 3 inch pipe before the maf, would you assume problems will occur?
Cause if the diameter of the pipe at the point of the maf is the same as stock, then it should calculate the proper lamda. Just allowing more of a ram air effect within the pipe.

Yes, if the ID where the MAF sits is the same as the oem then it will calculate correctly regardless of what’s before or after that section.

[tylerhart_21]

I just found an euro airbox with the maf yesterday. I have seen this on a GTI forum, with them smoothin out the inside of the airbox. They said it will help with the air flow and alittle with sound. I may try this out on mine US airbox first. However, what you to know what’s y’all’s opinion on this.

I believe the M Performance intake is smoothed out, and has the panel filter or the cone. From what I am seeing it’s a euro versus US airbox (depending on where you are at).

M Performance Intake Install

From this DIY I can’t get a good idea, but figure 11 looks like a modified part of the front housing. From this I am guessing it’s possible to DIY make this, just by smoothin out the airbox (will take time) and a K&N filter. With the euro airbox it’s just a K&N drop in.

Let me know what y’all think?

[chilledn52]

Just wanted to share the MAF adapter I’m working on. Needs some thicker walls and a slight alignment with the other end.
Will be tinkering some more soon

[MOD.Works]

You will get Lean codes.
The adapter looks good. but the air flow data from the MAF sensor is not correct.

[chilledn52]

Originally Posted by MOD.Works

You will get Lean codes.
The adapter looks good. but the air flow data from the MAF sensor is not correct.

Would you like to elaborate more, I would assume if I have a the same diameter as stock which is 75mm at the MAF location, should calculate the proper ratio.

[MOD.Works]

Originally Posted by chilledn52

Would you like to elaborate more, I would assume if I have a the same diameter as stock which is 75mm at the MAF location, should calculate the proper ratio.

I think you get more airflow outside the sensor area than the stock filter and MAF housing. The difference can be small and the dme adapts to it, in which case you no longer get codes.

I tried custom MAF housing last summer. It worked well. Until I put a big cone filter and a big velocity stack and then I got Lean codes.

[chilledn52]

Originally Posted by MOD.Works

I think you get more airflow outside the sensor area than the stock filter and MAF housing. The difference can be small and the dme adapts to it, in which case you no longer get codes.

I tried custom MAF housing last summer. It worked well. Until I put a big cone filter and a big velocity stack and then I got Lean codes.

Good to hear, ill keep that in mind, still going to try it out and let you guys know if I have problems.

[chilledn52]

Third iteration, Maf port needs to be sanded as it’s tight and won’t install. Besides that structurally strong. With the not so perfect circle it’s +/-1mm. When Maf fits I’ll shoot another update